Afghan and NATO officials are investigating the reports. However, NATO says it does not believe any civilians were killed in the incident.

Meanwhile, in southern Afghanistan Sunday, five civilians died when their vehicle hit a roadside bomb in Kandahar province.

The Zhari district police chief, Bismillah Khan, accused Taliban militants of laying the device close to an Afghan army base . He said the victims were driving to the grape fields to work when they were killed.

An organization representing about 100 aid agencies in Afghanistan, the Agency Coordinating Body for Afghan Relief, says 2,500 people have been killed in fighting this year, 1,000 of them civilians.

Insurgent attacks are blamed for two-thirds of all reported civilian casualties. Military air strikes and excessive force also are blamed.